Microemulsion System as a Steel Corrosion Inhibitor

• Published in: Corrosion (Houston, Tex.) Vol. 58; no. 9; pp. 723 - 727
• Main Authors: Castro Dantas, T.N., Ferreira Moura, E., Scatena, H., Dantas Neto, A.A.
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01.09.2002; NACE
• Subjects: Applied sciences; Butanol; Carbon steels; Corrosion; Corrosion effects; Corrosion inhibitors; Corrosion prevention; Electrochemistry; Exact sciences and technology; Hydrochloric acid; Inhibitors; Interfaces; Measurement techniques; Metals. Metallurgy; Microemulsions; n-Hexane; Surfactants; Corrosion resistance; Corrosion; Surface properties; Carbon steel; Chloric acid; Corrosion inhibition; Steel; Experimental study; Microemulsion; Thermodynamic properties; Corrosion protection; Corrosion inhibitor
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3277654

ABSTRACTA large variety of microstructures formed by surfactants in oil-in-water (O/W) systems are of great importance for adsorption phenomena in interfacial systems. Such structures are known as microemulsions: transparent, homogeneous, optically isotropic systems that form spontaneously and possess thermodynamic stability.1 Much attention has been given to microemulsions in industrial applications because of certain inherent characteristics, such as easy transportation of soluble compounds (active matter substances that are not readily soluble in aqueous or oil phases, used in industries). Because of their low viscosity, their technological uses must also be mentioned, such as in heavy oil emulsion breakdown in drilling wells,2 in heavy metal extraction from industrial effluents,3 and as vehicles for active compounds in drugs,4 among other applications. Surfactants have been studied in recent years as inhibitors of steel corrosion in acidic environments.5-12 The scarcity of studies related to the use of surfactants in microemulsified media as inhibitors of corrosion of metallic surfaces, such as iron and steel, and the difficulty in solubilizing some surfactants have prompted this work, as far as the electrochemical and corrosive behavior of carbon steel in contact with such microemulsified systems is concerned. The microemulsion acts as a transportation medium for an inhibitor, which is not readily soluble, in addition to increasing the contact area between the surfactant molecules and the metal surface. The objective of the present work is to study the effect of the dodecylammonium bromide (DDAB) surfactant on the corrosion inhibition of carbon steel (AISI 1010), once present in two different systems: System 1 (S-1) is a surfactant in diluted hydrochloric acid (HCl) (as a micellar solution) and System 2 (S-2) is a surfactant in HCl solution as the aqueous phase of a microemulsified system, which also comprises an organic compound as a dispersed oil phase and a